In the interest of conserving water, it has been found desirable to provide water faucet control which will automatically turn on and off under desired conditions. For example, some restrooms provide water faucets which turn on automatically when a person approaches the sink and turn off when the person leaves. This is most often found in areas where public washing facilities are available to prevent the water from being left on when the party finishes washing, thus wasting water and possibly causing mess.
The prior art systems are usually ultrasonic systems which detect the presence or absence of an object in front of the sink so as to activate or deactivate the water supply. Such systems have the disadvantage that they respond, not to the presence of hands in the washing area, but rather to a person in front of the sink. Thus, the water will continue flowing so long as the person is in front of the sink as may be the case when the washing party does not leave the area of the sink immediately after washing or when some object is placed in the front of the sink inadvertently. Furthermore, the ultrasonic systems are costly, temperature sensitive and may be activated by ambient noise such as is found in noisy airports or factory environments.